Some aircraft are capable of both vertical and forward flight, including helicopters and other rotor/wing aircraft. Rotor/wing aircraft may have an aerodynamic lifting surface that rotates to provide lift during vertical flight, and remains fixed in a stationary position to provide lift during forward flight. Examples of such rotor/wing aircraft include those aircraft embodiments disclosed in U.S. Pat. No. 5,454,530 issued to Rutherford et al. The aerodynamic lifting surface of such rotor/wing aircraft typically has an airfoil cross-section that is symmetrically rounded on the leading and trailing edges so that the direction of airflow can be easily reversed when the aircraft transitions from rotary wing (or vertical) flight to fixed-wing (or forward) flight.
Although desirable results have been achieved using such prior art methods, there is room for improvement. For example, the rounded trailing edge of the symmetric airfoil section produces aerodynamic drag that degrades the performance of the aircraft. Thus, novel apparatus that may reduce the drag on the airfoil during either fixed-wing (forward) flight or rotary (vertical) flight would be useful and desirable.